Sensor lead sealing and strain relief

ABSTRACT

A sensor system may include a wiring harness including at least one wire, a grommet, a nugget, a sensor, and a harness sleeve. The grommet may include at least one passageway configured to receive the wire. The nugget may include at least one terminal molded into the nugget and coupled to the wire. A mineral insulated cable may be coupled to the sensor and to the terminal. The harness sleeve may define at least one cavity configured to receive the nugget and at least a portion of the grommet. The harness sleeve may be coupled to the mineral insulated cable and may include a first crimp coupling the harness sleeve to the grommet. The exterior surface of the nugget may also include at least one radially disposed groove. The harness sleeve may also include a second crimp coupling the harness sleeve to the nugget, for example, about the radial groove. The first crimp may be configured to compress the grommet to provide a seal between the harness sleeve and the grommet and a seal between the grommet and the at least one wire of the harness wire. The second crimp and the molding of the terminal within the nugget may be configured to provide strain relief for the wiring harness.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/159,955, filed Mar. 13, 2009 and entitledEXHAUST GAS TEMPERATURE SENSOR LEAD SEALING AND STRAIN RELIEF, which isfully incorporated herein by reference.

FIELD

The present disclosure relates generally to sensors for internalcombustion engines. More specifically, the present disclosure may relateto a coupler for mechanically and/or electrically coupling a mineralinsulated cable to a wiring harness that reduces moisture intrusion,provides terminal location, provides stain relief and/or increases thecontinuous use temperature rating.

BACKGROUND

Internal combustion engines such as, but not limited to, diesel andgasoline engines, may include one or more sensors such as, but notlimited to, temperature sensors at least partially disposed within theexhaust gas system. For example, these temperature sensors may sense thetemperature of the exhaust gas and may be used, at least in part, by anengine control system to adjust one or more properties of the enginesuch as, but not limited to, air/fuel ratio, boost pressure, timing orthe like. Because of the operating environment, the temperature sensorsmay be exposed to relatively harsh conditions including, but not limitedto, vibration, exposure to debris, moisture and corrosive chemicals,large temperature ranges and relatively high continuous use operatingtemperatures. The conditions may degrade the performance of thetemperature sensors and may, ultimately, render the temperature sensorsunsuitable for their intended purpose.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present disclosure are set forth by thedescription of embodiments consistent therewith, which descriptionshould be considered in conjunction with the accompanying drawings,wherein:

FIG. 1 is a plan view of a sensor system coupled to a housing accordingto the present disclosure.

FIG. 2 is plan view of another embodiment of a sensor system coupled toa housing according to the present disclosure.

FIG. 3 is an exploded, perspective view of one embodiment of a couplerin accordance with the present disclosure.

FIG. 4 is a cross-sectional view of a grommet as shown in FIG. 3.

FIG. 5 is a sectional view of one embodiment of a grommet illustrated inFIG. 4 taken along lines V-V in accordance with the present disclosure.

FIG. 6 is an end view of the nugget in accordance with the presentdisclosure.

FIG. 7 is a top view of one embodiment of a connection between theterminal in nugget and the conductors of the mineral insulated (MI)cable in accordance with the present disclosure.

FIG. 8 is a side view of the connection shown in FIG. 7 in accordancewith the present disclosure.

FIG. 9 is an end view of the connection shown in FIG. 7 in accordancewith the present disclosure.

FIG. 10 is a side view of one embodiment of a nugget in accordance withthe present disclosure

FIG. 11 is a cross-sectional view of the nugget in accordance with thepresent disclosure in FIG. 10 taken along lines XI-XI.

FIG. 12 is a top view of the nugget shown in FIG. 10 in accordance withthe present disclosure.

FIG. 13 is a side view of a wiring harness in accordance with thepresent disclosure.

FIG. 14 is another side view of a wiring harness in accordance with thepresent disclosure.

FIG. 15 is a partially assembled view of one embodiment of a coupler inaccordance with the present disclosure.

FIG. 16 is a top view of the end of the MI cable in accordance with thepresent disclosure.

FIG. 17 is a side view of the end of the MI cable of FIG. 16 inaccordance with the present disclosure.

FIG. 18 is a top view of the connection between the sensor and themineral insulated cable in accordance with the present disclosure.

FIG. 19 is a close-up view of the connection between the sensor and themineral insulated cable shown in FIG. 18 in accordance with the presentdisclosure.

FIG. 20 is a side view of the connection between the sensor and the MIcable in accordance with the present disclosure.

FIG. 21 is a side view of the connection between the sensor and the MIcable filled with packing material in accordance with the presentdisclosure.

FIG. 22 is a side view of the connection between the sensor and the MIcable forming a tip in accordance with the present disclosure.

FIG. 23 is a top view of the end of the MI cable in accordance with thepresent disclosure.

FIG. 24 is a top view of the connection between the MI cable and thewiring harness including a grommet and a nugget in accordance with thepresent disclosure.

FIG. 25 is a side view of the connection between the MI cable and thewiring harness including a grommet and a nugget in accordance with thepresent disclosure.

FIG. 26 is a side view of the connection between the MI cable and thewiring harness including a grommet and a nugget within the harnesssleeve in accordance with the present disclosure.

DESCRIPTION

Referring now to the drawings, FIGS. 1 and 2 illustrate a sensor system10 consistent with at least one embodiment herein. The sensor system 10will be described in terms of an exhaust gas sensor system. For example,the sensor system 10 may comprise a temperature sensor such as, but notlimited to, an exhaust gas sensor system which may be configured to beused with an internal combustion engine such as, but not limited to, adiesel engine, a gasoline engine, or the like. The output of the exhaustgas sensor system may be received by an engine control unit (ECU) orengine control module (ECM) or the like to control one or moreparameters of the engine, for example, but not limited to, air/fuelratio, boost pressure, timing or the like. It should be appreciated,however, that the sensor system 10 may comprise other types of sensorsystems (e.g., but not limited to, a sensor system configured to detect,sense and/or monitor catalytic converter temperature, lubricanttemperature (such as, but not limited to, engine oil, transmission oil,differential oil, or the like), brake temperature, engine coolanttemperature, or the like). In addition, the sensor system 10 may includeother types of sensors, for example, sensors configured to detect, senseand/or monitor other parameters including, but not limited to, pressure,speed, position or the like.

The sensor system 10 may comprise a sensor 12 (e.g., but not limited to,a temperature sensor) coupled to a cable 11, a wire harness assembly 16,and a coupler 18 configured to couple the cable 11 to the wire harnessassembly 16. Optionally, a connector 20 may be provided to electricallyand/or mechanically couple the sensor system 10 (and in particular, thewire harness assembly 16) to a wiring loom or the like, and ultimatelyto at least a portion and/or subsystem of the ECU and/or ECM. The sensor12 may be configured to output a signal representative of the parameterbeing detected, sensed and/or monitored. The sensor 12 may be selecteddepending on the intended parameter to be detected, sensed and/ormonitored, the operating range, accuracy and/or precision desired. Forexample, the sensor 12 may comprise a temperature sensor configured tooutput a signal representative of the temperature of the exhaust gas,for example, the exhaust gas flowing through at least a portion of theexhaust gas system. According to at least one embodiment consistentherein, the temperature sensor 12 may include a resistive temperaturedetector (RTD).

The sensor system 10 may be configured to removably connect, mount, orotherwise secure the sensor 12 to a housing 13 (only a portion of whichis shown for clarity) such as, but not limited to, a portion of anexhaust pipe, down pipe, exhaust manifold, or the like. For example, thesensor system 10 may include a nut 22 and optionally a stop flange 24. Aportion of the sensor system 10 may be threaded to engage with athreaded aperture in the housing 13, for example, until the stop flange24 engages the housing 13 (for example, a shoulder or the like).

Because of the relative high operating temperatures of the exhaustsystem and the close proximity of the sensor 12 to the heat source, thesensor 12 may be electrically coupled to the wire harness assembly 16 orthe like using a cable 11. The cable 11 may comprise various types ofcables, such as, but not limited to, a mineral insulated (MI) cable orceramic insulator. For example, a MI cable 14 may comprise one or morewires disposed within a sheath 26 (e.g., a metal sheath) which areconfigured to electrically couple the sensor 12 to the wiring harness16. The sheath 26 may provide mechanical strength and/or protection tothe MI cable 14 and may also position the temperature sensor 12 and/orwiring harness 16 to prevent contact with other components. The mineralinsulation may provide the necessary thermal resistance for the sensorsystem 10 to withstand the high temperatures experienced within anexhaust system. The MI cable 14 may, however, be particular sensitive tomoisture absorption. For example, humidity in the ambient air may causea dielectric failure if the air has access within the MI cable 14. Asdiscussed herein, the sensor system 10 may include a coupler 18configured to reduce or eliminate water absorption of the MI cable 14,particularly from water being absorbed into the MI cable 14 from the endof the MI cable 14 connected to the wiring harness 16.

Turning now to FIG. 3, an exploded view of one embodiment of a coupler18 is generally illustrated. The coupler 18 may include a grommet 28, anugget 30 and a harness sleeve 32 coupled to the sheath 26 of the MIcable 14 which defines a cavity 52 configured to receive the grommet 28and nugget 30. The grommet 28 may form a high temperature seal betweenthe wires 34 a, 34 b of the wiring harness 16 and the harness sleeve 32.The grommet 28 may include at least one longitudinally disposedpassageway or cavity 36 configured to receive a portion of the wiringharness 16 and/or the wires 34 a, 34 b of the wiring harness 16.According to at least one embodiment, the grommet 28 may have agenerally cylindrical configuration comprising a first and a secondpassageway 36 a, 36 b as generally illustrated in FIGS. 4 and 5. Thepassageways 36 a, 36 b may be configured to receive the wires 34 a, 34 bas described herein. The grommet 28 may optionally include at least oneradially disposed protrusion or rib 38. The ribs 38 may be disposedalong the longitudinal length of the grommet 28 and may provide multiplesealing edges with the harness sleeve 32.

The grommet 28 may include a high temperature elastomer material. Theelastomer material may include a resiliently deformable materialconfigured to form a seal as described herein and may be configured tobe partially compressed by the harness sleeve 32. For example, thegrommet 28 may include a high temperature fluorocarbon rubber. Thefluorocarbon rubber may be configured to withstand temperatures of up to536 degrees F.

Referring back to FIG. 3, the nugget 30 may be configured to providestrain relief for the wire harness 16 and may also be configured toprovide the proper orientation and spacing of the wire terminals 48 a,48 b. For example, the terminals 48 a, 48 b may be coupled to the endsof the wires 34 a, 34 b of the wire harness 16 may be insert and/orover-molded into a high temperature plastic nugget 30 to fix theorientation of the terminals 48 a, 48 b for resistance welding with theMI cable 14 as generally illustrated in FIG. 6. The nugget 30 mayinclude, at least in part, a high temperature liquid crystal polymerconfigured to withstand the high ambient temperatures common to exhaustsystems (e.g., but not limited to, diesel exhaust systems). The materialof the nugget 30 may also be configured to provide electrical insulationand to bond the wire terminals 48 a, 48 b in the proper orientation andspacing for welding to the conductors inside the MI cable 14.

Turning now to FIGS. 7-9, one embodiment 48′ of at least one of theterminals 48 a, 48 b for coupling with the MI cable 14 is generallyillustrated. The terminal 48′ may include a first end 150 molded withinthe nugget 30 coupled to one or more of the wires 34 of the wiringharness 16, for example, via welding, crimping or the like. A second,generally opposite end 152 of the terminal 48′ may include a basket 154configured to receive a portion of the end of the conductors 60 of theMI cable 14. The basket 154 may facilitate alignment and may reduce anymovement of the terminals 48′ and the conductors 62 prior to and/orduring welding. As generally illustrated, the basket 154 may define apocket, cavity and/or groove configured to receive the ends of the MIcable 14. The basket 154 may include sidewall 156 that may be guideand/or generally locate the conductor 62 as generally illustrated inFIG. 9.

Referring now to FIGS. 10 and 11, the nugget 30 may optionally includean exterior shape configured to facilitate loading into an automatedwelding machine. For example, the nugget 30 may include one or moregenerally flat and/or planar regions 40 configured to facilitate loadinginto an automated welding machine. The flat region 40 may allow theautomatic welding machine to properly orientate the nugget 30, forexample, by providing an easily identifiable orientation feature. Whilethe nugget 30 is illustrated having a generally flat and/or planarregion 40, the nugget 30 may also include other shapes configured toallow provide an orientation feature such as, but not limited to, anindentation, protrusion, or the like. The nugget 30 may also include oneor more protrusions molded into the top and/or bottom of the nugget 30configured to maintain the terminals 48 separated during the moldingprocess and to prevent electrical short circuits.

As generally illustrated in FIGS. 10 and 12, the exterior surface 42 ofthe nugget 30 may optionally include one or more indentations or grooves44. The groove 44 may include a radial groove molded into a portion ofthe exterior surface 42 of the nugget 30. For example, consistent withat least one embodiment the groove 44 may be disposed about a proximalend region 46 of the nugget 30 which may be substantially adjacent tothe grommet 28 when assembled. The groove 44 may be configured to engageand/or mechanically couple the nugget 30 with harness sleeve 32, forexample, as generally illustrated in FIG. 26. The groove 44 may also beconfigured to self-align the nugget 30 into the harness sleeve 32 whenthe harness sleeve 32 is crimped as described herein.

Turning now to FIGS. 13 and 14, the wiring harness assembly 16 isillustrated with the grommet 28 and the nugget 30 secured thereto. Thegrommet 28 may be advanced over a portion of the wiring harness assembly16. The nugget 30 may also be insert-molded to the wiring harnessassembly 16. The terminals 48 a, 48 b may extend generally outwardlybeyond the nugget 30 and may be configured to be coupled to (forexample, welded to) the ends of the MI cable 14 (not shown). The nugget30 may be disposed substantially adjacent to the grommet 28. Accordingto at least one embodiment, the grommet 28 may directly contact againstthe proximal end region 46 of the nugget 30.

Referring back to FIG. 3, the harness sleeve 32 may include a first endregion 50 configured to be coupled to the sheath 26 of the MI cable 14.For example, the first end region 50 of the harness sleeve 32 may bewelded to a proximal end of the sheath 26. The harness sleeve 28 maydefine at least one cavity 52 configured to receive at least a portionof the grommet 28 and nugget 30 as generally illustrated in FIG. 15. Thecavity 52, grommet 28 and/or nugget 30 may be configured to form aninterference type or a friction fit. The cavity 52 may also haveinterior dimensions slightly larger than the outer dimensions of thegrommet 28 and/or nugget 30 such that the grommet 28 and/or nugget 30are readily received within the cavity 52 while providing a closetolerance, for example, of less than 10%, less than 5%, or less than 2%.The cavity 52 may optionally include step or tapered/conical region 54.The tapered region 54 may be configured to abut against a portion of thenugget 30, thereby preventing over-insertion of the nugget 30 in thecavity 52 and thereby reducing the potential for the terminals 48 a, 48b to short against the harness sleeve 32.

Once the grommet 28 and nugget 30 are received within the cavity 52 ofthe harness sleeve 32, the harness sleeve 32 may be crimped to form amechanical connection. For example, the harness sleeve 32 may be crimpedabout a portion overlaying the grommet 28 to form a first crimp 56 whichmay compress the elastomer material of the grommet 28. In thenon-compressed state, the passageway 36 of the grommet 28 may beconfigured to readily received the harness wire 16 and/or wires 34 a, 34b and may have an outer size and/or shape configured to be readilyreceived in the cavity 52 of the harness sleeve 32 to facilitateassembly of the sensor system 10. The first crimp 56 between the harnesssleeve 32 and the grommet 28 may compress the elastomer material of thegrommet 28 thereby substantially eliminating any clearance providedbetween the grommet 28 and the wires 34 a, 34 b of the wire harnessassembly 16 and forming a seal between the grommet 28 and the wireharness assembly 16. The first crimp 56 may also substantially eliminateany clearance provided between the grommet 28 and the harness sleeve 32thereby forming a seal.

The harness sleeve 32 may also be crimped about a portion overlaying thenugget 30 to form a second crimp 58. The second crimp 58 between theharness sleeve 32 and the nugget 30 may generally secure the nugget 30to the harness sleeve 32 and, along with the bonding of the terminals 48a, 48 b to the nugget 30, may provide strain relief for the wire harness16. According to at least one embodiment, the second crimp 58 may belocated about the radial groove 44 in the nugget 30 and may alsofacilitate alignment of the nugget 30 with respect to harness sleeve 32.

Turning now to FIGS. 16-22, one embodiment illustrating the system andmethod for coupling the sensor 12 to the MI cable 14 is generally shown.As generally illustrated in FIGS. 16 and 17, a distal end of the MIcable 14 may include conductors 62. The conductors 62 may be coupled tothe corresponding leads 60 of the sensor 12 as generally illustrated inFIGS. 18 and 19. According to one embodiment, the conductors 62 andleads 60 may be electrically and/or mechanically secured to each othervia one or more crimps, welds, or the like 64 and may be disposed withina sensor sleeve 66 as generally illustrated in FIG. 20. The sensorsleeve 66 may be secured to the MI cable 14, for example, by welding,and adhesive or the like. The sensor sleeve 66 may be filled withpacking material 68 such as, but not limited to, magnesium oxide (MgO),aluminum oxide, or boron nitride powder as generally illustrated in FIG.21. Once filled, the distal end of the sensor sleeve 66 may be crimpedand/or welded to form a tip 70 surrounding the sensor 12 as generallyillustrated in FIG. 22. The filled sensor 66 may be oxidized prior towelding, for example, at 650 degrees F. minimum.

Turning now to FIGS. 23-26, one embodiment illustrating the system andmethod for coupling the MI cable 14 to the wiring harness 16 isgenerally shown. For example, FIG. 23 generally illustrates the proximalend of the MI cable 14 including conductors 62. The conductors 62 may becoupled to the terminals 48 molded into the nugget 30 as generallyillustrate in FIGS. 24 and 25. The terminals 48 may receive theconductors 62 of the MI cable 14 (for example, within the baskets 154 asgenerally illustrated in FIGS. 7-9) and the may be electrically and/ormechanically secured, for example, via one or more crimps, welds,adhesives or the like 64. Once the terminals 48 and conductors 62 aresecured, the cavity 52 of the harness sleeve 32 may be advanced over thenugget 30 and at least a portion of the MI cable 14 and the grommet 28as generally illustrated in FIG. 26. The harness sleeve 32 may bealigned with the nugget 30 using, for example, the step 54 and/or thegroove 44. Once aligned, the first and second crimps 56, 58 may beformed in the harness sleeve 32 to seal and/or secure the harness sleeve32 to the grommet 28 and/or the nugget 30. The harness sleeve 32 mayalso be secured to sheath 26 of the MI cable 14, for example, bywelding, and adhesive or the like 72.

While the wiring harness 16 has been illustrated having two wires 34 a,34 b, it should be appreciated that wiring harness 16 may have fewerthan or greater than two wires 34 a, 34 b. For example, the wiringharness 16 may include one wire, three wires, four wires or the like.The grommet 28 and/or the nugget 30 may therefore be configured toreceive greater than or fewer than two wires 34 a, 34 b. Similarly, theMI cable 14 may have fewer than or greater than two wires and/orterminals.

Accordingly, consistent with at least one embodiment herein, a sensorsystem may comprise a sensor coupled to a cable, a wire harnessassembly, and a coupler configured to couple the cable to the wireharness assembly. The coupler may include a grommet, a nugget, and aharness sleeve. The grommet may include a high temperature seal betweenthe wires of the wiring harness and the harness sleeve. Crimping thegrommet into the harness sleeve compresses the elastomer eliminating theclearance provided for easy assembly thus achieving a seal. The nuggetmay be over-molded to the terminals of the wire harness and may beconfigured to provide the proper orientation and spacing of the wireterminals. A wide shallow groove may be molded around the outside of thenugget to provide a mechanism of attaching the nugget to the harnesssleeve. The mechanical crimping of the nugget in the harness sleeve andthe bonding of the terminals inside the nugget may provide strain relieffor the wire harness. The high temperature materials allow the sensorjunction to be shorter and closer to the heat source. Attaching the wireharness to the cable may be done by resistance welding wire terminals tothe conductors of the cable. The wire harness may be capable ofwithstanding pull force without breaking weld joints between the wireterminals and the conductors within the cable and may provide robuststrain relief for the wire harness. The material selection andcombination may permit a higher continuous use temperature due tothermal conduction, convection and radiation.

According to at least one embodiment consistent herein, the presentdisclosure may include a sensor system comprising a wiring harnesscomprising at least one wire, a grommet comprising at least onepassageway configured to receive the at least one wire, a nuggetcomprising at least one terminal molded into the nugget, a sensor; acable coupled to the sensor and to the at least one terminal; and aharness sleeve defining at least one cavity configured to receive thenugget and at least a portion of the grommet, wherein the harness sleeveincludes a first crimp coupling the harness sleeve to the grommet toform a seal.

According to yet another aspect, the present disclosure may feature asystem comprising a housing and a sensor system. The sensor system maycomprise a sensor configured to be coupled to the housing; a wiringharness comprising at least one wire; a grommet comprising at least onepassageway configured to receive the at least one wire; a nuggetcomprising at least one terminal molded into the nugget, the at leastone terminal coupled to the at least one wire; a cable coupled to thetemperature sensor and to the at least one terminal; and a harnesssleeve defining at least one cavity configured to receive the nugget andat least a portion of the grommet, wherein the harness sleeve is coupledto the cable and includes a first crimp coupling the harness sleeve tothe grommet.

In yet a further aspect, the present disclosure may feature a sensorsystem comprising a sensor coupled to a cable; a wire harness assembly;and a coupler configured to couple the cable to the wire harnessassembly. The coupler may comprise a nugget over-molded to the terminalsof the wire harness to provide an orientation and spacing of the wireterminals. The nugget may further comprise a wide shallow radial grooveabout the outside of the nugget. The coupler may also include a grommetcomprising an elastomeric material and a harness sleeve coupled to thecable. The harness sleeve may comprise a cavity to receive the nuggetand at least a portion of the grommet; a first crimp compressing theelastomer material of the grommet to form a seal between the wires ofthe wiring harness and the harness sleeve; and a second crimp alignedwith the radial groove in the nugget, the second crimp securing theharness sleeve to the nugget, wherein the second crimp and theovermolding of the terminals inside the nugget provide strain relief forthe wire harness.

In an addition aspect, the present disclosure may feature a method ofassembling a sensor system. The method may comprise advancing at leastone wire of a wiring harness through at least one passageway of agrommet, the at least one wire having a at least one terminal coupled toa distal end; molding a nugget over a portion of the at least oneterminal; coupling a conductor of a cable to the at least one terminal;coupling the cable to a harness sleeve and to a sensor; receiving thenugget and at least a portion of the grommet within a cavity of theharness sleeve; and coupling the harness sleeve to the grommet for forma seal.

The present disclosure has been described in an illustrative manner. Itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than of limitation.The features and aspects described with reference to particularembodiments disclosed herein may be susceptible to combination and/orapplication in various other embodiments described herein. Suchcombinations and/or applications of such described features and aspectsto such other embodiments are contemplated herein. Additionally, theembodiments disclosed herein are susceptible to numerous variations andmodifications without materially departing from the spirit of thedisclosed subject matter. Accordingly, the present disclosure hereinshould not be considered to be limited to the particular embodimentsdisclosed herein.

1. A sensor system comprising: a wiring harness comprising at least onewire; a grommet comprising at least one passageway configured to receivesaid at least one wire; a nugget comprising at least one terminal moldedinto said nugget, said at least one terminal coupled to said at leastone wire, wherein said nugget is disposed proximate a distal end regionof said at least one wire and wherein said grommet is adjacent to saidnugget; a sensor; a cable coupled to said sensor and comprising at leastone conductor coupled to said at least one terminal; and a harnesssleeve coupled to said cable, said harness sleeve defining at least onecavity to receive said nugget and at least a portion of said grommetwithin, wherein said harness sleeve includes a first crimp coupling saidharness sleeve to said grommet.
 2. The sensor system of claim 1, whereinan exterior surface of said grommet includes at least one radiallydisposed rib.
 3. The sensor system of claim 1, wherein said grommetincludes a first and a second passageway configured to receive a firstand a second wire of said wiring harness.
 4. The sensor system of claim1, wherein said harness sleeve includes a second crimp coupling saidharness sleeve to said nugget.
 5. The sensor system of claim 4, whereinan exterior surface of said nugget includes at least one radiallydisposed groove, wherein said second crimp couples said harness sleeveto said nugget about said radial groove and locates said nugget withinsaid cavity.
 6. The sensor system of claim 1, wherein an inner surfaceof said cavity comprises a stepped region configured to locate saidnugget with respect to said cavity, said stepped region having across-sectional area less than a cross-sectional area of an end regionof said nugget.
 7. The sensor system of claim 1, wherein said grommet isabutting against a proximal end region of said nugget.
 8. The sensorsystem of claim 1, wherein said first crimp is configured to compresssaid grommet to provide a seal between said harness sleeve and saidgrommet and a seal between said grommet and said at least one wire ofsaid harness wire.
 9. The sensor system of claim 1, wherein said nuggetincludes at least one geometric feature configured to facilitate loadingand locking of said nugget in said harness sleeve.
 10. The sensor systemof claim 1, wherein said sensor comprises a temperature sensor.
 11. Thesensor system of claim 10, wherein said temperature sensor comprises aresistive temperature detector.
 12. The sensor system of claim 1,wherein said cable is a mineral insulated cable.
 13. The sensor systemof claim 1, wherein said sensor is selected from the group consisting ofa pressure sensor, a speed sensor and a position sensor.
 14. A method ofassembling a sensor system comprising: advancing at least one wire of awiring harness through at least one passageway of a grommet, said atleast one wire having at least one terminal coupled to a distal end;molding a nugget over a portion of said at least one terminal; couplinga conductor of a cable to said at least one terminal; coupling saidcable to a harness sleeve and to a sensor; receiving said nugget and atleast a portion of said grommet within a cavity of said harness sleeve;and coupling said harness sleeve to said grommet for forming a seal. 15.The method of claim 14, wherein coupling said harness sleeve to saidgrommet comprises crimping said harness sleeve against said grommet. 16.The method of claim 14, further comprising coupling said harness sleeveto said nugget.
 17. The method of claim 16, wherein coupling saidharness sleeve to said nugget comprises crimping said harness sleeve tosaid nugget, wherein coupling said harness sleeve to said nugget reducesstrain to said sensor.
 18. A system comprising: a housing; and a sensorsystem comprising: a sensor coupled to a cable; a wire harness assemblycomprising at least one wire; and a coupler coupling said cable to saidwire harness assembly, said coupler comprising: a nugget over-molded toat least one terminal coupled to said at least one wire of said wireharness to provide an orientation and spacing of said at least oneterminal, said nugget further comprising a radial groove about theoutside of said nugget; a grommet comprising an elastomeric material,wherein said grommet is adjacent to said nugget; and a harness sleevecoupled to said cable, said harness sleeve comprising: a cavity toreceive said nugget and at least a portion of said grommet within; afirst crimp compressing said elastomer material of the grommet to form aseal between said at least one wire of said wiring harness and saidharness sleeve; and a second crimp aligned with said radial groove insaid nugget, said second crimp securing said harness sleeve to thenugget, wherein said second crimp and said overmolding of said at leastone terminal inside said nugget provide strain relief for said wireharness.
 19. The system of claim 18, wherein said housing comprises anexhaust system.
 20. The system of claim 19, wherein said sensor isselected from the group consisting of a temperature sensor, a pressuresensor, a speed sensor and a position sensor.